Semiconductor devices of this type are increasingly expected to have smaller size in recent years. For example, a package of a semiconductor chip and an interposer that are integrated with each other is mounted on a printed wiring board made of organic material such as a motherboard, namely, a CSP structure, is in practical use.
The semiconductor device in Patent Document 1 is an example of the CSP structure including a package in which a semiconductor chip is connected to an interposer made of organic material (resin). The interposer has a plurality of through holes, and solder balls are exposed at upper and lower surfaces of the interposer through the through holes. An external connection pad provided on the semiconductor chip is connected to an upper end of a solder post of the interposer. A lower end of the solder post is connected to a pad of the motherboard with a solder ball, for example. In this configuration, the packaged semiconductor device has a size only slightly larger than the size of the semiconductor chip. The size is regarded as almost the minimum.